Transmission device, receiving device, and data processing method

ABSTRACT

The present technology relates to a transmission device, a receiving device, and a data processing method that enable bandwidth control over PLPs when one frequency band includes the plurality of PLPs. The transmission device determines the number of cells of a component to be transmitted by each of PLPs such that the number of cells in an entire physical layer frame including the plurality of PLPs matches a sum of the number of cells of the plurality of PLPs, and transmits a broadcast stream including the physical layer frame. The present technology can be applied to, for example, a system for transmitting a broadcast stream including a physical layer frame including a plurality of PLPs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/741,863, filed Jan. 4, 2018, the entire contents of which areincorporated herein by reference. U.S. application Ser. No. 15/741,863is a National Stage of PCT/JP2016/075938, filed Sep. 5, 2016, and claimsthe benefit of priority from Japanese Application No. 2015-184540, filedSep. 17, 2015.

TECHNICAL FIELD

The present technology relates to a transmission device, a receivingdevice, and a data processing method, and particularly relates to atransmission device, a receiving device, and a data processing methodthat enable bandwidth control over PLPs when one frequency band includesthe plurality of PLPs.

BACKGROUND ART

It has been determined that the ATSC (Advanced Television SystemsCommittee) 3.0, which is one of the next-generation terrestrialbroadcasting standards, will mainly employ IP/UDP, i.e., the method ofusing IP (Internet Protocol) packets including UDP (User DatagramProtocol) packets (hereinafter referred to as IP transmission method)for data transmission, instead of TS (Transport Stream) packets.Moreover, broadcasting standards other than ATSC 3.0 are also expectedto employ the IP transmission method in the future.

Here, transmission data such as content can be transmitted in units ofPLPs (Physical Layer Pipes) (for example, refer to NPL 1). In ATSC 3.0,moreover, one frequency band (for example, a frequency band of 6 MHzcorresponding to one channel (physical channel)) includes one or aplurality of PLPs (Physical Layer Pipes).

CITATION LIST Non Patent Literature [NPL 1]

ETSI EN 302 755 V1.2.1 (2010-10)

SUMMARY Technical Problem

However, since there is no established technological method forincluding a plurality of PLPs in one frequency band, there has been ademand for a proposal for performing bandwidth control over PLPs whenone frequency band includes the plurality of PLPs.

The present technology has been made in view of the foregoingcircumstances and enables bandwidth control over PLPs when one frequencyband includes the plurality of PLPs.

Solution to Problem

A transmission device according to a first aspect of the presenttechnology includes a processing unit and a transmission unit. Theprocessing unit determines the number of cells of a component to betransmitted by each of PLPs (Physical Layer Pipes) such that the numberof cells in an entire physical layer frame including the plurality ofPLPs matches a sum of the number of cells of the plurality of PLPs. Thetransmission unit transmits a broadcast stream including the physicallayer frame.

The transmission device according to the first aspect of the presenttechnology may be an independent device or may be an internal blockconstituting one device. Further, a data processing method according tothe first aspect of the present technology is a data processing methodcorresponding to the above-described transmission device according tothe first aspect of the present technology.

In the transmission device and the data processing method according tothe first aspect of the present technology, the number of cells of acomponent to be transmitted by each of PLPs is determined such that thenumber of cells in an entire physical layer frame including theplurality of PLPs matches a sum of the number of cells of the pluralityof PLPs. A broadcast stream including the physical layer frame istransmitted.

A receiving device according to a second aspect of the presenttechnology includes a receiving unit and a processing unit. Thereceiving unit receives a broadcast stream including a physical layerframe which includes a plurality of PLPs and in which the number ofcells of a component transmitted by each of the PLPs is allocated suchthat the number of cells in the entire physical layer frame matches asum of the number of cells of the plurality of PLPs. The processing unitprocesses the physical layer frame.

The receiving device according to the second aspect of the presenttechnology may be an independent device or may be an internal blockconstituting one device. Further, a data processing method according tothe second aspect of the present technology is a data processing methodcorresponding to the above-described receiving device according to thesecond aspect of the present technology.

In the receiving device and the data processing method according to thesecond aspect of the present technology, a broadcast stream including aphysical layer frame which includes a plurality of PLPs and in which thenumber of cells of a component transmitted by each of the PLPs isallocated such that the number of cells in the entire physical layerframe matches a sum of the number of cells of the plurality of PLPs isreceived. The physical layer frame is processed.

Advantageous Effects of Invention

According to the first aspect and the second aspect of the presenttechnology, bandwidth control over PLPs can be performed when onefrequency band includes the plurality of PLPs.

Note that the effects described herein are not necessarily limitative,and any of the effects described in the present disclosure may beexhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an exemplary configuration of atransmission system to which the present technology is applied.

FIG. 2 is a diagram illustrating an exemplary configuration of atransmission device in FIG. 1.

FIG. 3 is a diagram illustrating an exemplary configuration of areceiving device in FIG. 1.

FIG. 4 is a diagram for describing an overview of bandwidth control overPLPs.

FIG. 5 is a diagram illustrating a structure of a physical layer frame.

FIG. 6 is a diagram illustrating an example of parameters of a subframe.

FIG. 7 is a diagram illustrating an example of parameters of a PLP.

FIG. 8 is a diagram illustrating a segment control unit.

FIG. 9 is a diagram for describing a segment bandwidth change method anda segment division method when a scene change occurs.

FIG. 10 is a diagram for describing data control using NRT content.

FIG. 11 is a diagram illustrating a list of bandwidth control methods ofthe present technology.

FIG. 12 is a diagram for describing bandwidth control when a bandwidthcontrol method 1 is employed.

FIG. 13 is a diagram illustrating a relation between transmission dataand the physical layer frame.

FIG. 14 is a diagram for describing bandwidth control when a bandwidthcontrol method 2 is employed.

FIG. 15 is a diagram for describing bandwidth control when a bandwidthcontrol method 2B is employed.

FIG. 16 is a diagram for describing bandwidth control when a bandwidthcontrol method 3 is employed.

FIG. 17 is a diagram for describing bandwidth control when a bandwidthcontrol method 3A is employed.

FIG. 18 is a diagram for describing bandwidth control when a bandwidthcontrol method 4 is employed.

FIG. 19 is a diagram for describing bandwidth control when a bandwidthcontrol method 4A is employed.

FIG. 20 is a diagram for describing bandwidth control when a bandwidthcontrol method 4B is employed.

FIG. 21 is a flowchart for describing a flow of data processing on atransmission side.

FIG. 22 is a flowchart for describing a detailed flow of schedulingprocessing.

FIG. 23 is a flowchart for describing a flow of data processing on areceiving side.

FIG. 24 is a diagram illustrating another exemplary configuration of thetransmission device.

FIG. 25 is a diagram illustrating an exemplary configuration of acomputer.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the present technology will be describedwith reference to the drawings. Note that the description will be madein the following order.

1. System Configuration

2. Overview of Bandwidth Control over PLPs to Which Present Technologyis Applied

3. Specific Examples of Bandwidth Control 4. Flow of Processing Executedby Each Device 5. Modification 6. Computer Configuration <1. SystemConfiguration> (Exemplary Configuration of Transmission System)

FIG. 1 is a diagram illustrating a configuration of one embodiment of atransmission system to which the present technology is applied. Notethat the “system” means a group of a plurality of devices logicallygathered.

In FIG. 1, a transmission system 1 includes a transmission device 10 anda receiving device 20. This transmission system 1 performs datatransmission conforming to the digital broadcasting standard employingthe IP transmission method, such as ATSC 3.0.

The transmission device 10 transmits content via a transmission path 30.For example, the transmission device 10 transmits a broadcast stream asa digital broadcast signal via the transmission path 30. The broadcaststream includes (components such as) video and audio constituting thecontent of a television program or the like as well as signaling.

The receiving device 20 receives and outputs the content transmittedfrom the transmission device 10 via the transmission path 30. Forexample, the receiving device 20 receives the digital broadcast signalfrom the transmission device 10, and obtains the (components such as)video and audio constituting the content as well as the signaling fromthe broadcast stream. The receiving device 20 then reproduces a movingimage and sound of the content of the television program or the like.

Note that although only one receiving device 20 is illustrated in thetransmission system 1 in FIG. 1 for ease of description, a plurality ofreceiving devices 20 can be provided and digital broadcast signalstransmitted by the transmission device 10 can be simultaneously receivedby the plurality of receiving devices 20 via the transmission path 30.

Further, the transmission path 30 in the transmission system 1 may beterrestrial broadcasting or may be, for example, satellite broadcastingusing broadcasting satellites (BSs) or communications satellites (CSs),cable broadcasting using cables (CATV), or the like.

(Exemplary Configuration of Transmission Device)

FIG. 2 is a diagram illustrating an exemplary configuration of thetransmission device 10 in FIG. 1.

In FIG. 2, the transmission device 10 includes a scheduler 101, afirst-system processing unit, a second-system processing unit, aphysical-layer processing unit 106, and a transmission unit 107. Thefirst-system processing unit includes a data obtaining unit 102-1,encoders 103-1 to 103-3, a multiplexer 104-1, and a PLP processing unit105-1. The second-system processing unit includes a data obtaining unit102-2, encoders 103-4 and 103-5, an NRT processing unit 103-6, amultiplexer 104-2, and a PLP processing unit 105-2.

Note that although the transmission device 10 in FIG. 2 can performprocessing so as to include a plurality of PLPs in one frequency band(e.g., a frequency band of 6 MHz corresponding to one channel (physicalchannel)), description will be given of the case where the transmissiondevice 10 performs processing so as to include two PLPs, i.e., PLP#1(e.g., a normal PLP) and PLP#2 (e.g., a robust PLP), in one frequencyband for ease of description. In the transmission device 10 in FIG. 2,in other words, the processing related to the normal PLP#1 is performedby the first-system processing unit, while the processing relating tothe robust PLP#2 is performed by the second-system processing unit. Notethat in ATSC 3.0, up to 64 PLPs can be arranged in one frequency band.

The scheduler 101 performs processing related to the control overencoding performed by the encoder 103-1 to the NRT processing unit 103-6and processing related to the bandwidth control over the PLPs performedby the PLP processing unit 105-1 and the PLP processing unit 105-2.

Further, physical layer information is inputted to the scheduler 101.This physical layer information includes the total number of cells andmodulation parameters for each PLP. The total number of cells indicatesthe number of cells in an entire physical layer frame (PHY Frame).

Here, the total number of cells is a parameter that is uniquelydetermined when the structure of the physical layer frame (e.g., framelength) is determined. Further, a cell is one set of encoded I/Qcomponents in a constellation.

Specifically, the physical layer frame includes a bootstrap (BS), apreamble, and a payload. ATSC 3.0 defines that the length of thebootstrap is 2 ms (=0.5 ms×4). Further, the length of the preamble andthe payload can be obtained by subtracting the length of the bootstrap(2 ms) from the length of the entire physical layer frame.

Further, the preamble and the payload include data cells, L1 signalingcells, pilot cells, and Null cells. The number of these cells can bedetermined by modcod (e.g., a modulation method, a code length, and acode rate), which is determined for each PLP, and the modulationparameters such as an FFT size, a guard interval length, a pilotpattern, and the number of carriers, which are determined for eachsubframe.

The total number of cells can be obtained by using these relations. Notethat the detailed structure of the subframes will be described laterwith reference to FIGS. 5 to 7. Further, the total number of cells inthe physical layer information can be transmitted as information(L1B_L1_Detail_total_cells) included in the signaling of the physicallayer.

Further, the modulation parameters include parameters such as amodulation method for each PLP (e.g., PLP#1 and PLP#2). Note that oncebroadcasting is started, the modulation parameters are basically fixed.This is because changing the modulation parameters changes thereceivable range of the digital broadcast signal transmitted from thetransmission device 10.

The data obtaining unit 102-1 obtains data of components (e.g., video,audio, and subtitles) constituting content of a television program orthe like, and supplies the data to the encoder 103-1, the encoder 103-2,and the encoder 103-3.

Note that in the following description, (data of) a component to beprocessed by the encoder 103-1 will be referred to as a component C1,(data of) a component to be processed by the encoder 103-2 will bereferred to as a component C2, and (data of) a component to be processedby the encoder 103-3 will be referred to as a component C3.

The data obtaining unit 102-2 obtains data of components (e.g., video,audio, and subtitles) constituting the content of the television programor the like, and supplies the data to the encoder 103-4, the encoder103-5, and the NRT processing unit 103-6.

Note that in the following description, (data of) a component to beprocessed by the encoder 103-4 will be referred to as a component C4,(data of) a component to be processed by the encoder 103-5 will bereferred to as a component C5, and (data of) a component to be processedby the NRT processing unit 103-6 will be referred to as a component C6(NRT content).

Here, the encoder 103-1, the encoder 103-2, and the encoder 103-3, whichserve as the first-system processing unit, and the encoder 103-4, theencoder 103-5, and the NRT processing unit 103-6, which serve as thesecond-system processing unit, supply corresponding encoding difficultylevel information to the scheduler 101. The encoding difficulty levelinformation indicates the encoding difficulty level according to thecomponent to be processed.

That is, for example, the encoder 103-1 supplies, to the scheduler 101,the encoding difficulty level information indicating the encodingdifficulty level of the component C1, such as a moving image withintense movement or a moving image close to a still image. Similarly,the encoder 103-2 to the NRT processing unit 103-6 supply, to thescheduler 101, the corresponding encoding difficulty level informationregarding the component C2 to the component C6.

The scheduler 101 is supplied with the encoding difficulty levelinformation from each of the encoder 103-1 to the NRT processing unit103-6. On the basis of, for example, the corresponding encodingdifficulty level information, the scheduler 101 determines the number ofcells to be allocated to the component C1 to the component C6 (thenumber of cells of each component) to be transmitted by each PLP (e.g.,PLP#1 and PLP#2).

Here, the number of cells is determined such that a large number ofcells (code amount) is allocated to a moving image of which encodingdifficulty level is high, for example, a moving image with intensemovement, while a small number of cells (code amount) is allocated to amoving image of which encoding difficulty level is low, for example, amoving image close to a still image. Further, each PLP, for example, thenormal PLP#1 and the robust PLP#2, has different modulation parameters.By using the modulation parameters, the code amounts (hereinafterreferred to as target code amounts) of the component C1 to the componentC6 to be processed by the encoder 103-1 to the NRT processing unit 103-6can be calculated from the number of cells of each component.

The target code amounts calculated in this way are each supplied to theencoder 103-1 to the NRT processing unit 103-6.

On the basis of the target code amount supplied from the scheduler 101,the encoder 103-1 performs encoding corresponding to a given encodingmethod on the data of the component C1 supplied from the data obtainingunit 102-1 and supplies the data to the multiplexer 104-1. Note,however, that the data of the component C1 processed by the encoder103-1 is processed in units of segments corresponding to the target codeamount.

Here, a segment (hereinafter also referred to as segment S) is a controlunit determined by a segment length T and a bandwidth W. The bit rate isconstant in each segment S (constant bitrate (CBR)), and the code amountis changed in units of segments. Note that the detailed structure of thesegments will be described later with reference to FIGS. 8 and 9.

Similarly, on the basis of the target code amounts supplied from thescheduler 101, the encoder 103-2 and the encoder 103-3 perform encodingon each of the data of the component C2 and the component C3 suppliedfrom the data obtaining unit 102-1, and supply the data to themultiplexer 104-1. Note, however, that the data of the component C2processed by the encoder 103-2 and the data of the component C3processed by the encoder 103-3 are processed in units of segmentscorresponding to the respective target code amounts.

Further, on the basis of the target code amounts supplied from thescheduler 101, the encoder 103-4 to the NRT processing unit 103-6perform encoding on each of the data of the component C4 to thecomponent C6 supplied from the data obtaining unit 102-2, and supply thedata to the multiplexer 104-2. Note, however, that the data of thecomponent C4 processed by the encoder 103-4, the data of the componentC5 processed by the encoder 103-5, and the data of the component C6processed by the NRT processing unit 103-6 are processed in units ofsegments corresponding to the respective target code amounts.

That is, the scheduler 101 dynamically changes the code amounts in thesegments S by variably controlling at least one of the segment length Tand bandwidth W of each segment S, as the processing in units ofsegments corresponding to the target code amounts performed by theencoder 103-1 to the NRT processing unit 103-6.

The multiplexer 104-1 multiplexes the data of the component C1 suppliedfrom the encoder 103-1, the data of the component C2 supplied from theencoder 103-2, and the data of the component C3 supplied from theencoder 103-3, and supplies the resultant multiplexed stream to the PLPprocessing unit 105-1.

The multiplexer 104-2 multiplexes the data of the component C4 suppliedfrom the encoder 103-4, the data of the component C5 supplied from theencoder 103-5, and the data of the component C6 supplied from the NRTprocessing unit 103-6, and supplies the resultant multiplexed stream tothe PLP processing unit 105-2.

Further, the scheduler 101 calculates the number of cells of PLP#1 andthe number of cells of PLP#2 on the basis of the number of cells of thecomponent C1 to the component C6.

Here, the total number of cells included in the physical layerinformation represents the number of cells in the entire physical layerframe, and the number of cells in the entire physical layer frame(N_(total)) is equal to the sum of the number of cells of each PLP, asindicated by the following equation (1).

[Math. 1]

N _(total) =ΣNi  (1)

Note that in the equation (1), N_(total) on the left side represents thenumber of cells in the entire physical layer frame. Further, N_(i) onthe right side represents the number of cells of each PLP, and irepresents the PLP number.

In the configuration in FIG. 2, moreover, the number of cells in theentire physical layer frame (N_(total)) is equal to the sum of thenumber of cells of PLP#1 and the number of cells of PLP#2. Therefore,the number of cells of PLP#1 and the number of cells of PLP#2 arecalculated by, for example, allocating the number of cells in the entirephysical layer frame to PLP#1 and PLP#2 according to the number of cellsof the component C1 to the component C6.

Among the number of cells of each PLP calculated in this way, the numberof cells of PLP#1 is supplied to the PLP processing unit 105-1, and thenumber of cells of PLP#2 is supplied to the PLP processing unit 105-2.

On the basis of the number of cells of PLP#1 supplied from the scheduler101, the PLP processing unit 105-1 performs bandwidth control over PLP#1by processing the multiplexed stream supplied from the multiplexer104-1. In this way, the transmission data corresponding to the number ofcells of PLP#1 is supplied to the physical-layer processing unit 106.

On the basis of the number of cells of PLP#2 supplied from the scheduler101, the PLP processing unit 105-2 performs bandwidth control over PLP#2by processing the multiplexed stream supplied from the multiplexer104-2. In this way, the transmission data corresponding to the number ofcells of PLP#2 is supplied to the physical-layer processing unit 106.

The physical-layer processing unit 106 generates a physical layer frame(PHY Frame) on the basis of the transmission data corresponding to thenumber of cells of PLP#1 supplied from the PLP processing unit 105-1 andthe transmission data corresponding to the number of cells of PLP#2supplied from the PLP processing unit 105-2. Note, however, that thenumber of cells in the entire physical layer frame matches the sum ofthe number of cells of PLP#1 and the number of cells of PLP#2. Note thatthe physical layer frame includes the bootstrap (BS), the preamble, andthe payload, and the transmission data of PLP#1 and PLP#2 are arrangedin this payload.

The physical layer frame generated by the physical-layer processing unit106 is supplied to the transmission unit 107.

The transmission unit 107 performs IFFT (Inverse Fast Fourier Transform)on the physical layer frame supplied from the physical-layer processingunit 106 and performs D/A conversion (Digital to Analog Conversion) onthe resultant OFDM (Orthogonal Frequency Division Multiplexing) signal.Then, the transmission unit 107 modulates the OFDM signal, which hasbeen converted from the digital signal to the analog signal, into an RF(Radio Frequency) signal, and transmits the RF signal as the digitalbroadcast signal of the IP transmission method through an antenna 121.

The transmission device 10 is configured as described above. Note thatalthough FIG. 2 illustrates the case where the device on thetransmission side is configured by the transmission device 10, i.e., onedevice, for convenience of description, the device on the transmissionside may be configured as a transmission system including a plurality ofdevices having each function of the blocks in FIG. 2.

Further, although the transmission device 10 in FIG. 2 illustrates theconfiguration corresponding to the two PLPs, i.e., PLP#1 and PLP#2, whenone frequency band (e.g., a frequency band of 6 MHz) includes three ormore PLPs, system processing units corresponding to the number of PLPsjust need to be provided.

(Exemplary Configuration of Receiving Device)

FIG. 3 is a diagram illustrating an exemplary configuration of thereceiving device 20 in FIG. 1.

In FIG. 3, the receiving device 20 includes a receiving unit 201, ademodulation processing unit 202, a demultiplexer 203, a decoder 204,and an output unit 205.

The receiving unit 201 receives, through an antenna 221, the digitalbroadcast signal of the IP transmission method transmitted from thetransmission device 10 via the transmission path 30. The receiving unit201 then performs frequency conversion from the RF signal into an IF(Intermediate Frequency) signal and supplies the signal to thedemodulation processing unit 202.

The demodulation processing unit 202 performs demodulation processing(e.g., OFDM demodulation) on the signal supplied from the receiving unit201. Further, the demodulation processing unit 202 performs errorcorrection processing on the demodulated signal obtained by thedemodulation processing, and supplies the multiplexed stream obtained asthe result of the processing to the demultiplexer 203.

The demultiplexer 203 demultiplexes the multiplexed stream supplied fromthe demodulation processing unit 202 into data of components (video,audio, and subtitles), and supplies the data to the decoder 204.

The decoder 204 decodes the data of the components supplied from thedemultiplexer 203 according to a given decoding method and supplies thedata to the output unit 205.

The output unit 205 includes, for example, a display unit and a speaker.The display unit displays the moving image corresponding to the videodata supplied from the decoder 204. Further, the speaker outputs soundcorresponding to the audio data supplied from the decoder 204. Note thatthe output unit 205 may output the video and audio data supplied fromthe decoder 204 to external equipment.

The receiving device 20 is configured as described above. Note that thereceiving device 20 may be a fixed receiver such as a televisionreceiver, a set top box (STB), or a video recorder, or may be a mobilereceiver such as a mobile phone, a smartphone, or a tablet terminal.Further, the receiving device 20 may be in-vehicle equipment mounted ina vehicle.

<2. Overview of Bandwidth Control over PLPs to Which Present Technologyis Applied>(Overview of Bandwidth Control over PLPs)

FIG. 4 is a diagram for describing the overview of the bandwidth controlover the PLPs in the transmission device 10.

FIG. 4 illustrates that the PLP#1 and PLP#2 bandwidths arranged in thephysical layer frame (PHY Frame) are changed through the bandwidthcontrol over the PLPs, with the direction heading from the upper side tothe lower side in the figure representing the direction of time.

Note that in FIG. 4, the physical layer frame includes the bootstrap(BS), the preamble, and the payload, and the transmission data of PLP#1and PLP#2 are arranged in the payload. Further, since the size of thephysical layer frame is determined and the number of cells in the entirephysical layer frame is constant, controlling the bandwidths of the PLPsdoes not change the total number of cells of PLP#1 and PLP#2 but changesthe ratio of the number of cells of PLP#1 to the number of cells ofPLP#2. That is, the bit rates of PLP#1 and PLP#2 change according to theratio of the number of cells.

That is, the number of cells of PLP#1 and the number of cells of PLP#2are approximately the same in the physical layer frame at time t1.Thereafter, at time t2 after time t1, the number of cells of PLP#2increases in the physical layer frame while the number of cells of PLP#1decreases by the increased amount. Then, at time t3 after time t2, thenumber of cells of PLP#1 contrarily increases while the number of cellsof PLP#2 decreases by the increased amount.

Thereafter, similarly at time t4 to time t7, when the number of cells ofPLP#1 increases in the physical layer frame, the number of cells ofPLP#2 decreases accordingly, while when the number of cells of PLP#2increases, the number of cells of PLP#1 decreases accordingly.

In this way, the bandwidth control over the PLPs is performed bychanging the number of cells of PLP#1 and the number of cells of PLP#2on the assumption that the number of cells in the entire physical layerframe is constant.

Note that in practice, the physical layer frame includes the bootstrap(BS), the preamble, and one or more subframes as illustrated in FIG. 5,and the data of one or a plurality of PLPs (e.g., PLP#1 and PLP#2) arearranged in this subframe.

Here, parameters that can be changed for each subframe are theparameters as illustrated in FIG. 6, such as, for example, the FFT size(L1D_fft_size), the guard interval length (L1D_guard_interval), or thepilot pattern (L1D_scattered_pilot_pattern). Further, parameters thatcan be changed for each PLP are the parameters as illustrated in FIG. 7,such as the code length (L1_plp_fec_type), the modulation method(L1D_plp_mod), or the code rate (L1D_plp_cod).

(Structure of Segment)

FIG. 8 is a diagram illustrating the structure of the segment S.

The segment S is a control unit determined by the segment length T andthe bandwidth W. The bit rate is constant within this segment S, and thecode amount is changed in units of segments.

Here, each segment S starts from a RAP (Random Access Point). RAPindicates the position of a frame that can obtain one complete imageonly with this frame, such as, for example, an I frame in a GOP (Groupof Pictures).

Further, when a scene change occurs, the I frame is inserted. In thesegment S, as a result, there exist two I frames of which generated codeamount is large. Since only half of the generated code amount can beallocated to each I frame when the bandwidth is constant, this resultsin the deterioration of the image quality. Note, however, that the scenechange occurs at the time when there is no correlation between a frameof interest, which is the current interest, and the preceding frame,which is temporally continuous with the frame of interest.

In the present technology, therefore, when the scene change occurs, thesegment S is processed using a segment bandwidth change method or asegment division method so as to be able to minimize the deteriorationof the image quality resulting from the insertion of the I frame at theoccurrence of the scene change.

Specifically, as illustrated in A of FIG. 9, the segment S processingusing the segment bandwidth change method widens the bandwidth W of thesegment S up to bandwidth W′ when the scene change occurs. Thisincreases the bandwidth within the segment S (temporarily). In thiscase, even when an I frame or a P frame is inserted, it is possible tominimize the deterioration of the image quality at the occurrence of thescene change because of the bandwidth being increased within the segmentS. Other than the scene change, moreover, when any previouslyunpredictable change in the generated code amount occurs, the bandwidthcan be increased or decreased in a similar way.

Further, as illustrated in B of FIG. 9, when the scene change occurs,the segment S processing using the segment division method terminatesthe target segment S at this point and starts a new segment S. In thiscase, even in the middle of the processing of a GOP in the targetsegment S, the processing of this GOP is forcibly terminated (terminatedat segment length T′ (T′<T)) and processing of a new GOP is restarted inthe new segment S. Then, processing of the I frame at the head isperformed in the new segment S, for example.

In this way, when the scene change occurs, the target segment S isterminated even in the middle of the predetermined segment length, andthe new segment S is started (that is, by dividing the segment S). As aresult, for example, the two I frames do not exist in the segment S andthe deterioration of the image quality at the occurrence of the scenechange can be minimized. Other than the scene change, moreover, when anypreviously unpredictable increase in the generated code amount occurs, anew segment S can be started in a similar way.

In the present technology, as described above, processing is basicallyperformed in units of segments. However, in a situation where the normalprocessing in units of segments is not applicable (e.g., a situationwhere bandwidth needs to be increased), such as, for example, at thetime when a scene change occurs, the segment S is exceptionallyprocessed according to a predetermined method such as the segmentbandwidth change method, the segment division method, or the like.

Note that in the case of employing a hierarchical encoding technology,there is an advantage that decoding and synchronization processing arefacilitated with the components of different layers having the samesegment length T.

(Data Control Using NRT Content)

FIG. 10 is a diagram for describing data control using the NRT content.

Incidentally, the bandwidth of the physical layer (PHY) conforming tothe general broadcasting standard is a fixed bit rate. In order toachieve this, data encoding is controlled such that the quality (mainlyimage quality) of each content is optimized within a range in which thegenerated code amount of the data of components (video and audio)constituting the content of a television program or the like does notexceed the fixed bit rate of the physical layer.

At this time, Null packets are inserted into portions that areinsufficient for the fixed bit rate so that the portions are adjusted tothe fixed bit rate. In the physical layer, moreover, the generated codeamount is reduced using a header compression technology or a variablelength header technology, for example. However, when the generated codeamount is insufficient for the fixed bit rate, Null packets areinserted.

Such a situation is illustrated in A of FIG. 10. A waveform L in A ofFIG. 10 illustrates a relation of the generated code amount of thedigital broadcasting conforming to a general broadcasting standard tothe elapse of time t. The generated code amount is in the vertical axis,and the elapse of time t is in the horizontal axis. The area in a rangeZ₀ equal to or less than the waveform L is the total generated codeamount. That is, with a generated code amount Sx as the maximum value,the generated code amount changes as indicated by the waveform L. Thegenerated code amount Sx is the fixed bit rate in the physical layer.

However, since transmission needs to be performed at the fixed bit ratein the physical layer and the code amount becomes insufficient at thetiming other than the timing of the generated code amount Sx, which isthe maximum value of the waveform L, Null packets are inserted. That is,at the timing other than the generated code amount Sx, which is themaximum value, a range Z₁ is the code amount of invalid data, i.e., Nullpackets, as illustrated in A of FIG. 10. The range Z₁ is equal to orgreater than the waveform L and smaller than the maximum value of thegenerated code amount Sx.

Nevertheless, ATSC 3.0 requires effective use of the limited bandwidth.Since Null packets, which are invalid data, may cause a reduction in thetransmission efficiency, it is desirable that the Null packets are notused. Therefore, transmission efficiency can be improved by transmittingnot only real time (RT) data such as the components C but also the dataof the NRT content that is of non real time (NRT).

That is, at the timing other than the generated code amount Sx, which isthe maximum value, a range Z₁₂ is the code amount of the data of the NRTcontent instead of the Null packets, as illustrated in B of FIG. 10. Therange Z₁₂ is the range between the waveform L and the maximum value ofthe generated code amount Sx.

Note, however, that there are cases where it is not possible to includethe data of the NRT content that completely corresponds to the codeamount of the Null packets. Therefore, a range Z₁₁ above the range Z₁₂is the code amount of the reduced Null packets. In this way, the rangeZ₀ and the range Z₁₂ become valid packets to be transmitted. As aresult, almost the entire range of the generated code amount Sx, whichis the maximum value of the fixed bit rate, can be used up, andtherefore the transmission efficiency can be improved.

In the present technology, moreover, paying attention to the fact thatthe NRT content (component C6) is non-real-time data, the bandwidth ofthe data of the NRT content (component C6) is made to vary freely. Thatis, the bandwidth of the NRT content (component C6) is controlleddepending on the generated code amounts of the data of the othercomponents (components C1 to C5) which are real-time data, so that thebandwidths of the other components (components C1 to C5) arepreferentially secured.

In this way, by using the bandwidth of the NRT content (component C6)as, so to speak, a margin, the real-time bandwidth control can befacilitated more. Note that since the NRT content (component C6) isnon-real-time data, no problem occurs even when the bandwidth thereof istemporarily set to 0 (zero), for example.

Note that the inventor of the present application has already proposedthe method for transmitting the data of the NRT content instead of Nullpackets in Japanese Patent Application No. 2014-127064.

<3. Specific Examples of Bandwidth Control> (List of Bandwidth ControlMethods)

FIG. 11 is a diagram illustrating a list of bandwidth control methods ofthe present technology.

The bandwidth control methods of the present technology are determinedby a combination of the bandwidth W and the segment length T of thesegment S in each component, the segment switching time, and handling atthe occurrence of the scene change.

Here, the bandwidth W of each segment S comes in two types, i.e.,“constant” and “variable.” “Constant” indicates that the width of thebandwidth W of the segment S of each component is constant, while“variable” indicates that the width of the bandwidth W of the segment Sof each component changes with time.

Further, the segment length T comes in two types, i.e., “constant” and“constant/variable.” “Constant” indicates that the segment length T ofthe segment S of each component is constant, while “constant/variable”indicates that the segment length T of the segment S of each componentis constant or changes with time.

Further, the segment switching time comes in two types, i.e.,“simultaneous” and “individual.” “Simultaneous” indicates that the timeat which the segment S of each component is switched is the same, while“individual” indicates that the time at which the segment S of eachcomponent is switched varies. Note, however, that the types of thesegment length T and the types of the segment switching time correlatewith each other; the segment switching time is “simultaneous” when thesegment length T is “constant,” while the segment switching time is“individual” when the segment length T is “constant/variable.”

Further, the handling at the occurrence of the scene change comes in twotypes, i.e., “segment bandwidth change method” and “segment divisionmethod.” The “segment bandwidth change method” indicates that thehandling at the occurrence of the scene change of each component is doneby the segment bandwidth change method (A of FIG. 9). The “segmentdivision method” indicates that the handling at the occurrence of thescene change of each component is done by the segment division method (Bof FIG. 9). Note that in the table in FIG. 11, the cases where thehandling at the occurrence of the scene change is not specificallydetermined are denoted by “-.”

In the table in FIG. 11, eight bandwidth control methods are determineddepending on the combinations of these types.

In a bandwidth control method 1, control is performed such that thebandwidth W is “constant,” the segment length T is “constant,” and thesegment switching time is “simultaneous.”

A bandwidth control method 2 and a bandwidth control method 2B have incommon with each other, in that the control is performed such that thebandwidth W is “constant,” the segment length T is “constant/variable,”and the segment switching time is “individual.” On the other hand, thedifference is that only in the bandwidth control method 2B, the controlis performed such that the handling at the occurrence of the scenechange is done by the “segment division method.”

A bandwidth control method 3 and a bandwidth control method 3A have incommon with each other, in that the control is performed such that thebandwidth W is “variable,” the segment length T is “constant,” and thesegment switching time is “simultaneous.” On the other hand, thedifference is that only in the bandwidth control method 3A, the controlis performed such that the handling at the occurrence of the scenechange is done by the “segment bandwidth change method.”

A bandwidth control method 4, a bandwidth control method 4A, and abandwidth control method 4B have in common with each other, in that thecontrol is performed such that the bandwidth W is “variable,” thesegment length T is “constant/variable,” and the segment switching timeis “individual.” On the other hand, the difference is that in thebandwidth control method 4A, the control is performed such that thehandling at the occurrence of the scene change is done by the “segmentbandwidth change method,” while in the bandwidth control method 4B, thecontrol is performed such that the handling at the occurrence of thescene change is done by the “segment division method.”

The specific examples of each bandwidth control method illustrated inthe table in FIG. 11 will be described below in order.

(1) Bandwidth Control Method 1

FIG. 12 is a diagram for describing the bandwidth control when thebandwidth control method 1 is employed.

In FIG. 12, the horizontal axis represents time t, and the directionheading from the left side to the right side in the figure representsthe direction of time. Further, the vertical axis represents the numberof cells (No of Cells), indicating that the higher the position in thefigure, the greater the number of cells. That is, the relation betweenthe time axis and the number of cells in FIG. 12, which is representedby the physical layer frame, can be represented as illustrated in FIG.13.

Referring back to the description in FIG. 12, the component C1 to thecomponent C6 correspond to the component C1 to the component C6processed by the encoder 103-1 to the NRT processing unit 103-6 in FIG.2.

That is, the component C1 represents the component processed by theencoder 103-1 (FIG. 2), and a segment S11, a segment S12, a segment S13,. . . , and a segment S1 t (t is an integer equal to or greater than 1)are processed in sequence as the segments S of this component C1.

Similarly, the component C2 to the component C5 represent the componentsprocessed by the encoder 103-2 to the encoder 103-5 (FIG. 2). Then, asegment S21, . . . , and an S2 t (t is an integer equal to or greaterthan 1) are processed in sequence as the segments S of the component C2,and a segment S31, . . . , and a segment S3 t (t is an integer equal toor greater than 1) are processed in sequence as the segments S of thecomponent C3. Further, a segment S41, . . . , and an S4 t (t is aninteger equal to or greater than 1) are processed in sequence as thesegments S of the component C4, and a segment S51, . . . , and an S5 t(t is an integer equal to or greater than 1) are processed in sequenceas the segments S of the component C5.

Further, the component C6 represents the NRT content processed by theNRT processing unit 103-6 (FIG. 2), and a segment S61, . . . , and an S6t (t is an integer equal to or greater than 1) are processed in sequenceas the segments S of this component C6 (NRT content).

Note that in the following description, the components C1 to C6 will bereferred to as a component C when it is not necessary to particularlydistinguish among them. Further, the segments S11 to Sit, the segmentsS21 to S2 t, the segments S31 to S3 t, the segments S41 to S4 t, thesegments S51 to S5 t, and the segments S61 to S6 t will be referred toas a segment S when it is not necessary to particularly distinguishamong them. Further, the relation among them is also similar in FIGS. 14to 20 to be described later.

Here, in the bandwidth control method 1 in FIG. 12, the scheduler 101(FIG. 2) performs control such that the bandwidth W and the segmentlength T of the segment S are “constant” and the segment switching timeis “simultaneous.” That is, in the bandwidth control method 1, thebandwidth W and the segment length T of each segment S are “constant.”In each component C, therefore, the width in the vertical-axis directionand the width in the horizontal-axis direction are the same in theregion of each segment S determined by the bandwidth W and the segmentlength T (the region having a pattern that is different per segments ofeach component in the figure).

Further, since the segment switching time is “simultaneous” in thebandwidth control method 1, the segment S switching time in eachcomponent C is repeated every fixed period.

For example, paying attention to each segment S of the component C1, thesegment S11 starting at time t0 switches to the segment S12 at time t1,the segment S12 starting at time t1 switches to the segment S13 at timet2, and the segment S13 starting at time t2 switches to the segment S14at time t3. At this time, moreover, the bandwidth of each segment S inthe component C1 is constant.

Note, however, that in FIG. 12, the period from time t0 to time t1, theperiod from time t1 to time t2, and the period from time t2 to time t3are the same period. Note that although FIG. 12 illustrates the periodfrom time t0 to time t3 for convenience of description, the switchbetween the temporally continuous preceding and succeeding segments(e.g., the segment S14 and the segment S15) in the component C1 is alsoperformed in sequence every fixed period in the following periods.

Similarly, paying attention to each segment S of the component C2, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S21 and the segment S22, the segment S22and the segment S23) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C2 is constant.

Similarly, paying attention to each segment S of the component C3, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S31 and the segment S32, the segment S32and the segment S33) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C3 is constant.

Then, the respective segments S in the component C1 to the component C3processed by the encoder 103-1 to the encoder 103-3 are multiplexed bythe multiplexer 104-1, and the resultant multiplexed stream is processedas PLP#1 by the PLP processing unit 105-1.

Further, paying attention to each segment S of the component C4, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S41 and the segment S42, the segment S42and the segment S43) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C4 is constant.

Similarly, paying attention to each segment S of the component C5, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S51 and the segment S52, the segment S52and the segment S53) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C5 is constant.

Similarly, paying attention to each segment of the component C6 (NRTcontent), the switch between the temporally continuous preceding andsucceeding segments S (e.g., the segment S61 and the segment S62, thesegment S62 and the segment S63) is performed in sequence at each time t(e.g., time t1 and time t2) every fixed period. At this time, moreover,the bandwidth of each segment S in the component C6 is constant.

Then, the respective segments S in the component C4 to the component C6processed by the encoder 103-4 to the NRT processing unit 103-6 aremultiplexed by the multiplexer 104-2, and the resultant multiplexedstream is processed as PLP#2 by the PLP processing unit 105-2.

As described above, in the bandwidth control method 1 in FIG. 12, theswitch between the temporally continuous segments S in each component Cis performed simultaneously at each time t (e.g., time t1 and time t2)every fixed period.

Specifically, for example, at time t1, the switches between the segmentS11 and the segment S12 of the component C1, between the segment S21 andthe segment S22 of the component C2, between the segment S31 and thesegment S32 of the component C3, between the segment S41 and the segmentS42 of the component C4, between the segment S51 and the segment S52 ofthe component C5, and between the segment S61 and the segment S62 of thecomponent C6 are performed simultaneously.

Further, for example, at time t2, the switches between the segment S12and the segment S13 of the component C1, between the segment S22 and thesegment S23 of the component C2, between the segment S32 and the segmentS33 of the component C3, between the segment S42 and the segment S43 ofthe component C4, between the segment S52 and the segment S53 of thecomponent C5, and between the segment S62 and the segment S63 of thecomponent C6 are performed simultaneously.

The bandwidth control when the bandwidth control method 1 is employedhas been described above.

(2) Bandwidth Control Method 2

FIG. 14 is a diagram for describing the bandwidth control when thebandwidth control method 2 is employed.

Here, in the bandwidth control method 2 in FIG. 14, the scheduler 101(FIG. 2) performs control such that the bandwidth W is “constant,” thesegment length T is “constant/variable,” and the segment switching timeis “individual.” That is, in the bandwidth control method 2, thebandwidth W of each segment S is “constant” while the segment length Tthereof is “constant/variable.” In each component C, therefore, theregion of each segment S determined by the bandwidth W and the segmentlength T (the region having a pattern that is different per segments ofeach component in the figure) has the same width in the vertical-axisdirection but a different width in the horizontal-axis direction.

Further, since the segment switching time is “individual” in thebandwidth control method 2, the segment S switching time in eachcomponent C is not a fixed period.

For example, paying attention to each segment S of the component C1, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S11 and the segment S12, the segment S12and the segment S13) is performed in sequence at each time t (e.g., timet1 and time t2) every variable period. At this time, moreover, thebandwidth of each segment S in the component C1 is constant.

Similarly, paying attention to each segment S of the component C2, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S21 and the segment S22, the segment S22and the segment S23, the segment S23 and the segment S24) is performedin sequence at each time t (e.g., time other than time t1 and time t2)every variable period. At this time, moreover, the bandwidth of eachsegment S in the component C2 is constant.

Similarly, paying attention to each segment S of the component C3, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S31 and the segment S32, the segment S32and the segment S33, the segment S33 and the segment S34) is performedin sequence at each time t (e.g., time other than time t1 and time t2)every variable period. At this time, moreover, the bandwidth of eachsegment S in the component C3 is constant.

Then, the respective segments S in the component C1 to the component C3processed by the encoder 103-1 to the encoder 103-3 are multiplexed bythe multiplexer 104-1, and the resultant multiplexed stream is processedas PLP#1 by the PLP processing unit 105-1.

Further, paying attention to each segment S of the component C4, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S41 and the segment S42, the segment S42and the segment S43) is performed in sequence at each time t (e.g., timeother than time t1 and time t2) every variable period. At this time,moreover, the bandwidth of each segment S in the component C4 isconstant.

Similarly, paying attention to each segment S of the component C5, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S51 and the segment S52, the segment S52and the segment S53) is performed in sequence at each time t (e.g., timeother than time t1 and time t2) every variable period. At this time,moreover, the bandwidth of each segment S in the component C5 isconstant.

Similarly, paying attention to each segment of the component C6 (NRTcontent), the switch between the temporally continuous preceding andsucceeding segments S (e.g., the segment S61 and the segment S62, thesegment S62 and the segment S63) is performed in sequence at each time t(e.g., time other than time t1 and time t2) every variable period. Atthis time, moreover, the bandwidth of each segment S in the component C6is constant.

Then, the respective segments S in the component C4 to the component C6processed by the encoder 103-4 to the NRT processing unit 103-6 aremultiplexed by the multiplexer 104-2, and the resultant multiplexedstream is processed as PLP#2 by the PLP processing unit 105-2.

As described above, in the bandwidth control method 2 in FIG. 14, theswitch between the temporally continuous segments S in each component Cis not performed simultaneously but performed at each time t (e.g., timet1 and time t2) every variable period.

Specifically, for example, the switch between the segment S11 and thesegment S12 in the component C1 is performed at time t1, but the switchbetween the segments S is not performed in the component C2 to thecomponent C6 at this time. Further, for example, the switch between thesegment S12 and the segment S13 in the component C1 is performed at timet2, but the switch between the segments S is not performed in thecomponent C2 to the component C6 at this time.

Note that although everything will not be described to avoid repetition,the component C2 to the component C6 are also similar. When the switchbetween its own segments S is performed, there is no switch betweenother segments S in the other components C at this timing.

The bandwidth control when the bandwidth control method 2 is employedhas been described above.

(3) Bandwidth Control Method 2B

FIG. 15 is a diagram for describing the bandwidth control when thebandwidth control method 2B is employed.

The bandwidth control method 2B in FIG. 15 has in common with thebandwidth control method 2 (FIG. 14) in that the scheduler 101 (FIG. 2)performs control such that the bandwidth W is “constant,” the segmentlength T is “constant/variable,” and the segment switching time is“individual.” On the other hand, the bandwidth control method 2B isdifferent from the bandwidth control method 2 (FIG. 14) in that when thescene change occurs, processing is performed using the segment divisionmethod. This point will be mainly described below.

That is, in the bandwidth control method 2B, the bandwidth W of eachsegment S is “constant” while the segment length T thereof is“constant/variable.” In each component C, therefore, the region of eachsegment S determined by the bandwidth W and the segment length T (theregion having a pattern that is different per segments of each componentin the figure) has the same width in the vertical-axis direction but adifferent width in the horizontal-axis direction. Further, since thesegment switching time is “individual” in the bandwidth control method2B, the segment S switching time in each component C is not a fixedperiod.

Here, paying attention to each segment S of the component C1, when thescene change occurs at time t2 at which the segment S12 is beingprocessed, the segment S12 is forcibly terminated at this point even inthe middle of the predetermined segment length and the processing of thenew segment S13 is started according to the segment division method.This can minimize the deterioration of the image quality at theoccurrence of the scene change without two I frames existing in thesegment S, for example.

The bandwidth control when the bandwidth control method 2B is employedhas been described above.

(4) Bandwidth Control Method 3

FIG. 16 is a diagram for describing the bandwidth control when thebandwidth control method 3 is employed.

In the bandwidth control method 3 in FIG. 16, the scheduler 101 (FIG. 2)performs control such that the bandwidth W is “variable,” the segmentlength T is “constant,” and the segment switching time is“simultaneous.” That is, in the bandwidth control method 3, the segmentlength T of each segment S is “constant” while the bandwidth W thereofis “variable.” In each component C, therefore, the region of eachsegment S determined by the bandwidth W and the segment length T (theregion having a pattern that is different per segments of each componentin the figure) has the same width in the horizontal direction but adifferent width in the vertical direction.

Further, since the segment switching time is “simultaneous” in thebandwidth control method 3, the segment S switching time in eachcomponent C is repeated every fixed period.

For example, paying attention to each segment S of the component C1, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S11 and the segment S12, the segment S12and the segment S13) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C1 is variable and variesin each segment S.

Similarly, paying attention to each segment S of the component C2, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S21 and the segment S22, the segment S22and the segment S23) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C2 is variable and variesin each segment S.

Similarly, paying attention to each segment S of the component C3, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S31 and the segment S32, the segment S32and the segment S33) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C3 is variable and variesin each segment S.

Then, the respective segments S in the component C1 to the component C3processed by the encoder 103-1 to the encoder 103-3 are multiplexed bythe multiplexer 104-1, and the resultant multiplexed stream is processedas PLP#1 by the PLP processing unit 105-1.

Further, paying attention to each segment S of the component C4, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S41 and the segment S42, the segment S42and the segment S43) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C4 is variable and variesin each segment S.

Similarly, paying attention to each segment S of the component C5, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S51 and the segment S52, the segment S52and the segment S53) is performed in sequence at each time t (e.g., timet1 and time t2) every fixed period. At this time, moreover, thebandwidth of each segment S in the component C5 is variable and variesin each segment S.

Similarly, paying attention to each segment of the component C6 (NRTcontent), the switch between the temporally continuous preceding andsucceeding segments S (e.g., the segment S61 and the segment S62, thesegment S62 and the segment S63) is performed in sequence at each time t(e.g., time t1 and time t2) every fixed period. At this time, moreover,the bandwidth of each segment S in the component C6 is variable andvaries in each segment S.

Then, the respective segments S in the component C4 to the component C6processed by the encoder 103-4 to the NRT processing unit 103-6 aremultiplexed by the multiplexer 104-2, and the resultant multiplexedstream is processed as PLP#2 by the PLP processing unit 105-2.

As described above, in the bandwidth control method 3 in FIG. 16, theswitch between the temporally continuous segments S in each component Cis performed simultaneously at each time t (e.g., time t1 and time t2)every fixed period.

Specifically, for example, at time t1, the switches between the segmentS11 and the segment S12 of the component C1, between the segment S21 andthe segment S22 of the component C2, between the segment S31 and thesegment S32 of the component C3, between the segment S41 and the segmentS42 of the component C4, between the segment S51 and the segment S52 ofthe component C5, and between the segment S61 and the segment S62 of thecomponent C6 are performed simultaneously.

Further, for example, at time t2, the switches between the segment S12and the segment S13 of the component C1, between the segment S22 and thesegment S23 of the component C2, between the segment S32 and the segmentS33 of the component C3, between the segment S42 and the segment S43 ofthe component C4, between the segment S52 and the segment S53 of thecomponent C5, and between the segment S62 and the segment S63 of thecomponent C6 are performed simultaneously.

Note, however, that the bandwidth of each segment S in the component C1to the component C6 is variable and thus varies from segment S tosegment S in each component C.

The bandwidth control when the bandwidth control method 3 is employedhas been described above.

(5) Bandwidth Control Method 3A

FIG. 17 is a diagram for describing the bandwidth control when thebandwidth control method 3A is employed.

The bandwidth control method 3A in FIG. 17 has in common with thebandwidth control method 3 (FIG. 16) in that the scheduler 101 (FIG. 2)performs control such that the bandwidth W is “variable,” the segmentlength T is “constant,” and the segment switching time is“simultaneous.” On the other hand, the bandwidth control method 3A isdifferent from the bandwidth control method 3 (FIG. 16) in that when thescene change occurs, processing is performed using the segment bandwidthchange method. This point will be mainly described below.

That is, in the bandwidth control method 3A, the segment length T ofeach segment S is “constant” while the bandwidth W thereof is“variable.” In each component C, therefore, the region of each segment Sdetermined by the bandwidth W and the segment length T (the regionhaving a pattern that is different per segments of each component in thefigure) has the same width in the horizontal direction but a differentwidth in the vertical direction. Further, since the segment switchingtime is “simultaneous” in the bandwidth control method 3A, the segment Sswitching time in each component C is a fixed period.

Here, paying attention to each segment S of the component C1, when thescene change occurs at time t2, the bandwidth W of the segment S12 iswidened at this point according to the segment bandwidth change method.This increases the bandwidth within the segment S12 (temporarily). Inthis case, for example, even when an I frame or a P frame is inserted,it is possible to minimize the deterioration of the image quality at theoccurrence of the scene change because of the bandwidth being increasedwithin the segment S.

Further, in this example, although the bandwidths of the segment S22,the segment S32, the segment S42, and the segment S52 move upward inconjunction with the widening of the bandwidth W of the segment S12 attime t2, the scene change in the segment 12 can be handled withoutreducing the bandwidths of these segments S. This is because thebandwidth of the NRT content (component C6) is used as, so to speak, amargin.

The bandwidth control when the bandwidth control method 3A is employedhas been described above.

(6) Bandwidth Control Method 4

FIG. 18 is a diagram for describing the bandwidth control when thebandwidth control method 4 is employed.

In the bandwidth control method 4 in FIG. 18, the scheduler 101 (FIG. 2)performs control such that the bandwidth W is “variable,” the segmentlength T is “constant/variable,” and the segment switching time is“individual.” That is, in the bandwidth control method 4, the bandwidthW of each segment S is “variable,” and the segment length T thereof is“constant/variable.” In each component C, therefore, the region of eachsegment S determined by the bandwidth W and the segment length T (theregion having a pattern that is different per segments of each componentin the figure) does not have either the same width in the verticaldirection or the same width in the horizontal direction.

Further, since the segment switching time is “individual” in thebandwidth control method 4, the segment S switching time in eachcomponent C is not a fixed period.

For example, paying attention to each segment S of the component C1, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S11 and the segment S12, the segment S12and the segment S13) is performed in sequence at each time t (e.g., timet1 and time t2) every variable period. At this time, moreover, thebandwidth of each segment S in the component C1 is variable and variesin each segment S.

Similarly, paying attention to each segment S of the component C2, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S21 and the segment S22, the segment S22and the segment S23, the segment S23 and the segment S24) is performedin sequence at each time t (e.g., time other than time t1 and time t2)every variable period. At this time, moreover, the bandwidth of eachsegment S in the component C2 is variable and varies in each segment S.

Similarly, paying attention to each segment S of the component C3, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S31 and the segment S32, the segment S32and the segment S33, the segment S33 and the segment S34) is performedin sequence at each time t (e.g., time other than time t1 and time t2)every variable period. At this time, moreover, the bandwidth of eachsegment S in the component C3 is variable and varies in each segment S.

Then, the respective segments S of the component C1 to the component C3processed by the encoder 103-1 to the encoder 103-3 are multiplexed bythe multiplexer 104-1, and the resultant multiplexed stream is processedas PLP#1 by the PLP processing unit 105-1.

Further, paying attention to each segment S of the component C4, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S41 and the segment S42, the segment S42and the segment S43) is performed in sequence at each time t (e.g., timeother than time t1 and time t2) every variable period. At this time,moreover, the bandwidth of each segment S in the component C4 isvariable and varies in each segment S.

Similarly, paying attention to each segment S of the component C5, theswitch between the temporally continuous preceding and succeedingsegments S (e.g., the segment S51 and the segment S52, the segment S52and the segment S53) is performed in sequence at each time t (e.g., timeother than time t1 and time t2) every variable period. At this time,moreover, the bandwidth of each segment S in the component C5 isvariable and varies in each segment S.

Similarly, paying attention to each segment of the component C6 (NRTcontent), the switch between the temporally continuous preceding andsucceeding segments S (e.g., the segment S61 and the segment S62, thesegment S62 and the segment S63) is performed in sequence at each time t(e.g., time other than time t1 and time t2) every variable period. Atthis time, moreover, the bandwidth of each segment S in the component C6is variable and varies in each segment S.

Then, the respective segments S in the component C4 to the component C6processed by the encoder 103-4 to the NRT processing unit 103-6 aremultiplexed by the multiplexer 104-2, and the resultant multiplexedstream is processed as PLP#2 by the PLP processing unit 105-2.

As described above, in the bandwidth control method 4 in FIG. 18, theswitch between the temporally continuous segments S in each component Cis not performed simultaneously but performed at each time t (e.g., timet1 and time t2) every variable period.

Specifically, for example, the switch between the segment S11 and thesegment S12 in the component C1 is performed at time t1, but the switchbetween the segments S is not performed in the components C2 to C6 atthis time. Further, for example, the switch between the segment S12 andthe segment S13 in the component C1 is performed at time t2, but theswitch between the segments S is not performed in the components C2 toC6 at this time.

Note that although everything will not be described to avoid repetition,the components C2 to C6 are also similar. When the switch between itsown segments S is performed, there is no switch between other segments Sin the other components C at this timing.

The bandwidth control when the bandwidth control method 4 is employedhas been described above.

(7) Bandwidth Control Method 4A

FIG. 19 is a diagram for describing the bandwidth control when thebandwidth control method 4A is employed.

Here, the bandwidth control method 4A in FIG. 19 has in common with thebandwidth control method 4 (FIG. 18) in that the scheduler 101 (FIG. 2)performs control such that the bandwidth W is “variable,” the segmentlength T is “constant/variable,” and the segment switching time is“individual.” On the other hand, the bandwidth control method 4A isdifferent from the bandwidth control method 4 (FIG. 18) in that when thescene change occurs, processing is performed using the segment bandwidthchange method. This point will be mainly described below.

That is, in the bandwidth control method 4A, the bandwidth W of eachsegment S is “variable,” and the segment length T thereof is“constant/variable.” In each component C, therefore, the region of eachsegment S determined by the bandwidth W and the segment length T (theregion having a pattern that is different per segments of each componentin the figure) does not have either the same width in the verticaldirection or the same width in the horizontal direction. Further, sincethe segment switching time is “individual” in the bandwidth controlmethod 4A, the segment S switching time in each component C is not afixed period.

Here, paying attention to each segment S of the component C1, when thescene change occurs at time t2, the bandwidth W of the segment S12 iswidened at this point according to the segment bandwidth change method.This increases the bandwidth within the segment S12 (temporarily). Inthis case, for example, even when an I frame or a P frame is inserted,it is possible to minimize the deterioration of the image quality at theoccurrence of the scene change because of the bandwidth being increasedwithin the segment S.

Further, in this example, although the bandwidths of the segment S23,the segment S32, the segment S42, the segment S43, and the segment S53move upward in conjunction with the widening of the bandwidth W of thesegment S12 at time t2, the scene change in the segment 12 can behandled without reducing the bandwidths of these segments S. This isbecause the bandwidth of the NRT content (component C6) is used as, soto speak, a margin.

The bandwidth control when the bandwidth control method 4A is employedhas been described above.

(8) Bandwidth Control Method 4B

FIG. 20 is a diagram for describing the bandwidth control when thebandwidth control method 4B is employed.

The bandwidth control method 4B in FIG. 20 has in common with thebandwidth control method 4 (FIG. 18) in that the scheduler 101 (FIG. 2)performs control such that the bandwidth W is “variable,” the segmentlength T is “constant/variable,” and the segment switching time is“individual.” On the other hand, the bandwidth control method 4B isdifferent from the bandwidth control method 4 (FIG. 18) in that when thescene change occurs, processing is performed using the segment divisionmethod. This point will be mainly described below.

That is, in the bandwidth control method 4B, the bandwidth W of eachsegment S is “variable,” and the segment length T thereof is“constant/variable.” In each component C, therefore, the region of eachsegment S determined by the bandwidth W and the segment length T (theregion having a pattern that is different per segments of each componentin the figure) does not have either the same width in the verticaldirection or the same width in the horizontal direction. Further, sincethe segment switching time is “individual” in the bandwidth controlmethod 4A, the segment S switching time in each component C is not afixed period.

Here, paying attention to each segment S of the component C1, when thescene change occurs at time t2 at which the segment S12 is beingprocessed, the segment S12 is forcibly terminated at this point even inthe middle of the predetermined segment length and the processing of thenew segment S13 is started according to the segment division method.This can minimize the deterioration of the image quality at theoccurrence of the scene change without two I frames existing in thesegment S, for example.

The bandwidth control when the bandwidth control method 4B is employedhas been described above.

<4. Flow of Processing Executed by Each Device>

Next, the flow of processing executed by the transmission device 10 andthe receiving device 20 included in the transmission system 1 in FIG. 1will be described with reference to the flowcharts in FIG. 21 to FIG.23.

(Flow of Data Processing on Transmission Side)

First, a flow of data processing on the transmission side executed bythe transmission device 10 in FIG. 1 will be described with reference tothe flowchart in FIG. 21.

In step S101, the scheduler 101 performs scheduling processing. In thisscheduling processing, processing related to the control over encodingperformed by the encoder 103-1 to the NRT processing unit 103-6 andprocessing related to the bandwidth control over the PLPs performed bythe PLP processing unit 105-1 and the PLP processing unit 105-2 areperformed. Note that the details of the scheduling processing will bedescribed later with reference to the flowchart in FIG. 22.

In step S102, the encoder 103-1 to the NRT processing unit 103-6 performcomponent processing. In this component processing, the data of thecomponent C1 to the component C6 are processed (encoded) in units ofsegments corresponding to the target code amounts calculated by theprocessing in step S101.

Note that the data of the component C1 to the component C3 aremultiplexed by the multiplexer 104-1, while the data of the component C4to the component C6 are multiplexed by the multiplexer 104-2.

In step S103, the PLP processing unit 105-1 and the PLP processing unit105-2 perform PLP processing. In this PLP processing, the PLP processingunit 105-1 performs bandwidth control over PLP#1 on the basis of thenumber of cells of PLP#1 calculated by the processing in step S101.Further, the PLP processing unit 105-2 performs bandwidth control overPLP#2 on the basis of the number of cells of PLP#2 calculated by theprocessing in step S101.

In step S104, the physical-layer processing unit 106 performs physicallayer processing. In this physical layer processing, a physical layerframe in which the PLPs corresponding to the bandwidth control by theprocessing in step S103 are arranged in the payload is generated.

In step S105, the transmission unit 107 performs processing oftransmitting a digital broadcast signal. In this transmissionprocessing, the physical layer frame generated by the processing in stepS104 is processed and transmitted as the digital broadcast signal of theIP transmission method.

When the processing in step S105 ends, the data processing on thetransmission side in FIG. 21 ends.

The flow of the data processing on the transmission side has beendescribed above.

(Flow of Scheduling Processing)

Next, a flow of the detailed processing of the scheduling processingcorresponding to the processing in step S101 in FIG. 21 will bedescribed with reference to the flowchart in FIG. 22.

In step S121, the scheduler 101 obtains physical layer informationinputted thereto. This physical layer information includes the totalnumber of cells indicating the number of cells in the entire physicallayer frame and modulation parameters for each PLP.

In step S122, the scheduler 101 obtains encoding difficulty levelinformation supplied from each of the encoder 103-1 to the NRTprocessing unit 103-6.

In step S123, the scheduler 101 determines the number of cells of eachcomponent.

Here, for example, the number of cells of each component can bedetermined on the basis of the encoding difficulty level information andthe like obtained by the processing in step S122. Further, the targetcode amounts can be obtained from the number of cells of each componentby using the modulation parameters for each PLP obtained by theprocessing in step S121. The target code amounts obtained in this wayare each supplied to the encoder 103-1 to the NRT processing unit 103-6.

Further, for example, the number of cells of PLP#1 and the number ofcells of PLP#2 can be calculated on the basis of the number of cells ofeach component determined by the processing in step S123. Then, thenumber of cells of PLP#1 is supplied to the PLP processing unit 105-1,while the number of cells of PLP#2 is supplied to the PLP processingunit 105-2.

When the processing in step S123 ends, the processing returns to theprocessing in step S101 in FIG. 21 and the processing thereafter isexecuted.

The flow of the scheduling processing has been described above.

(Flow of Data Processing on Receiving Side)

Next, a flow of data processing on the receiving side executed by thereceiving device 20 in FIG. 1 will be described with reference to theflowchart in FIG. 23.

In step S201, the receiving unit 201 performs processing of receivingthe digital broadcast signal. In this receiving processing, the digitalbroadcast signal of the IP transmission method transmitted from thetransmission device 10 via the transmission path 30 is received.

In step S202, the demodulation processing unit 202 performs demodulationprocessing on the signal obtained by the processing in step S201. Inthis demodulation processing, OFDM demodulation, error correctionprocessing, and the like are performed. Note that the multiplexed streamobtained by this demodulation processing is demultiplexed into the dataof the components by the demultiplexer 203.

In step S203, the decoder 204 decodes the data of the componentsobtained by the processing in step S202 according to a given decodingmethod.

In step S204, the output unit 205 displays a moving image correspondingto the video data obtained by the processing in step S203. Further, theoutput unit 205 outputs sound corresponding to the audio data obtainedby the processing in step S203.

When the processing in step S204 ends, the data processing on thereceiving side in FIG. 23 ends.

The flow of the data processing on the receiving side has been describedabove.

<5. Modification> (Another Exemplary Configuration of TransmissionDevice)

Incidentally, ATSC 3.0 employs channel bonding in which a plurality ofchannels (frequency bands) are bonded and used. FIG. 24 illustrates anexemplary configuration of the transmission device 10 conforming to thischannel bonding. In the transmission device 10 in FIG. 24, the pluralityof channels (frequency bands) are bonded and used by the physical-layerprocessing unit 106.

Further, a frequency hopping method may be employed in the channelbonding. Here, the frequency hopping is a technology by which thefrequency band being used is changed at given time intervals with a viewto addressing fading and the like.

Note that in the above description, although the components have beenmainly described as the data that require securement of the bandwidthsfor ease of description, real-time data (e.g., service information (SI))other than non-real-time data such as the NRT content need thesecurement of the bandwidths. The bandwidth control over such real-timedata can also be performed in a similar way to the above-describedcomponents.

Further, although ATSC (ATSC 3.0 in particular), which is the methodemployed in the United States of America and the like, has beendescribed as the digital broadcasting standard in the above description,the present technology may be applied to the ISDB (Integrated ServicesDigital Broadcasting), the DVB (Digital Video Broadcasting), and thelike. The ISDB is the method employed in Japan and the like. The DVB isthe method employed in European countries and the like. Moreover, thepresent technology can be applied to satellite broadcasting such as BSs(Broadcasting Satellites) and CSs (Communications Satellites), cablebroadcasting such as cable television (CATV), and the like, in additionto the terrestrial broadcasting, as the digital broadcasting.

Further, the present technology can also be applied to the givenstandards (standards other than the digital broadcasting standards) andthe like which are defined on the assumption that the transmission pathother than the broadcasting network, i.e., a communication line(communication network) or the like such as, for example, the Internet,a telephone network, or the like is used as the transmission path. Inthis case, the communication line such as the Internet, the telephonenetwork, or the like can be used as the transmission path 30, while thetransmission device 10 can serve as a server provided on the Internet.Then, by including a communication function in the receiving device 20,the transmission device 10 performs processing in response to a requestfrom the receiving device 20.

<6. Computer Configuration>

The series of processing described above can be executed by hardware orsoftware. When the series of processing is to be executed by software, aprogram constituting the software is installed in a computer. FIG. 25 isa diagram illustrating an exemplary hardware configuration of thecomputer in which the program executes the series of processingdescribed above.

In a computer 900, a CPU (Central Processing Unit) 901, ROM (Read OnlyMemory) 902, and RAM (Random Access Memory) 903 are mutually connectedvia a bus 904. Moreover, an input/output interface 905 is connected tothe bus 904. An input unit 906, an output unit 907, a recording unit908, a communication unit 909, and a drive 910 are connected to theinput/output interface 905.

The input unit 906 includes a keyboard, a mouse, a microphone, and thelike. The output unit 907 includes a display, a speaker, and the like.The recording unit 908 includes a hard disk, non-volatile memory, andthe like. The communication unit 909 includes a network interface andthe like. The drive 910 drives a removable medium 911 such as a magneticdisk, an optical disk, a magneto-optical disk, semiconductor memory, orthe like.

In the computer 900 configured as above, the CPU 901 loads the programrecorded in the ROM 902 or the recording unit 908 into the RAM 903 viathe input/output interface 905 and the bus 904 and executes the program,through which the above-described series of processing is performed.

The program to be executed by the computer 900 (CPU 901) can be recordedand provided on the removable medium 911 as a package medium or thelike, for example. Further, the program can be provided via a wired orwireless transmission medium such as a local area network, the Internet,or digital satellite broadcasting.

In the computer 900, the program can be installed in the recording unit908 via the input/output interface 905 by attaching the removable medium911 to the drive 910. Further, the program can be received by thecommunication unit 909 via a wired or wireless transmission medium andinstalled in the recording unit 908. Otherwise, the program can beinstalled in advance in the ROM 902 or the recording unit 908.

Here, the processing performed by the computer according to the programin the present specification does not necessarily need to be performedin the time sequence following the order described as the flowcharts.That is, the processing performed by the computer according to theprogram also includes processing that is executed in parallel orindividually (e.g., parallel processing or processing by an object).Further, the program may be processed by a single computer (processor)or by a plurality of computers in a distributed manner.

Note that the embodiment of the present technology is not limited to theabove-described embodiment and various modifications can be made withoutdeparting from the gist of the present technology.

Further, the present technology can be configured as follows.

(1) A transmission device including:

a processing unit that determines the number of cells of a component tobe transmitted by each of PLPs (Physical Layer Pipes) such that thenumber of cells in an entire physical layer frame including theplurality of PLPs matches a sum of the number of cells of the pluralityof PLPs; and

a transmission unit that transmits a broadcast stream including thephysical layer frame.

(2) The transmission device according to (1),

in which the component is processed in units of segments, the segmentseach being determined by a segment length and a bandwidth.

(3) The transmission device according to (2),

in which the processing unit dynamically changes code amounts of thesegments by variably controlling at least one of the segment length andthe bandwidth for each segment.

(4) The transmission device according to (1),

in which each of the plurality of PLPs has a different modulationparameter.

(5) The transmssion device according to (2),

in which when a generated code amount of the component is changed, theprocessing unit increases or decreases a bandwidth within a targetsegment.

(6) The transmission device according to (2),

in which when a generated code amount of the component is increased, theprocessing unit terminates a target segment and starts a new segment.

(7) The transmission device according to (2),

in which when a non-real-time component is included as the component,the processing unit controls a bandwidth of a segment of thenon-real-time component according to a generated code amount of areal-time component.

(8) The transmission device according to any one of (1) to (7),

in which the number of cells in the entire physical layer frame is aparameter uniquely determined when a structure of the physical layerframe is determined.

(9) A data processing method in a transmission device, the dataprocessing method including the steps of:

by the transmission device,

determining the number of cells of a component to be transmitted by eachof PLPs such that the number of cells in an entire physical layer frameincluding the plurality of PLPs matches a sum of the number of cells ofthe plurality of PLPs; and

transmitting a broadcast stream including the physical layer frame.

(10) A receiving device including:

a receiving unit that receives a broadcast stream including a physicallayer frame, the physical layer frame which includes a plurality of PLPsand in which the number of cells of a component transmitted by each ofthe PLPs is allocated such that the number of cells in the entirephysical layer frame matches a sum of the number of cells of theplurality of PLPs; and

a processing unit that processes the physical layer frame.

(11) The receiving device according to (10),

in which each of the plurality of PLPs has a different modulationparameter.

(12) A data processing method in a receiving device, the data processingmethod including the steps of:

by the receiving device,

receiving a broadcast stream including a physical layer frame, thephysical layer frame which includes a plurality of PLPs and in which thenumber of cells of a component transmitted by each of the PLPs isallocated such that the number of cells in the entire physical layerframe matches a sum of the number of cells of the plurality of PLPs; and

processing the physical layer frame.

REFERENCE SIGNS LIST

1 Transmission system10 Transmission device20 Receiving device30 Transmission path

101 Scheduler

102-1, 102-2 Data obtaining unit

103-1 to 103-5 Encoder

103-6 NRT processing unit

104-1, 104-2 Multiplexer

105-1, 105-2 PLP processing unit106 Physical-layer processing unit107 Transmission unit201 Receiving unit202 Demodulation processing unit

203 Demultiplexer 204 Decoder

205 Output unit

900 Computer 901 CPU

1. A transmission device comprising: a processing unit that determinesthe number of cells of a component to be transmitted by each of PLPs(Physical Layer Pipes) such that the number of cells in an entirephysical layer frame including the plurality of PLPs matches a sum ofthe number of cells of the plurality of PLPs; and a transmission unitthat transmits a broadcast stream including the physical layer frame.